modification

(redirected from Modifications)
Also found in: Dictionary, Thesaurus, Medical, Legal, Acronyms.

modification

[‚mäd·ə·fə′kā·shən]
(cell and molecular biology)
In nucleic acid metabolism, any changes made to deoxyribonucleic acid or ribonucleic acid after their original incorporation into a polynucleotide chain.
(engineering)
A major or minor change in the design of an item, effected in order to correct a deficiency, to facilitate production, or to improve operational effectiveness.
(metallurgy)
Treatment of molten aluminum alloys containing 8-13% silicon with small amounts of a sodium fluoride or sodium chloride mixture; improves mechanical properties.
(science and technology)
Any change brought about by external or internal factors.

Modification

 

in biology, nonhereditary changes in the visible characters (phenotype) of an organism; these changes occur under the influence of altered environmental conditions.

Modifying factors in the environment (temperature, illumination, diet) act on the organism during sensitive periods of its development, precipitating changes in the organism’s internal makeup (for example, changes in hormone level) and altering the course of ontogeny. Modificational variation consists in changes within the limits of the genotypically conditioned norm of reaction. Depending on the temperature of its environment, the Himalayan rabbit may change from black in cold weather to rusty brown in mild temperatures to pure white in high temperatures. However, the coloration of the parent rabbits is not inherited by their young; only the capacity to change color according to temperature change is inherited.

In nature, modifications are, as a rule, adaptive reactions of organisms to environmental factors. Thus, in lake Sagittaria sagittifolia, the shape of the leaves depends on where they grow: the above-water leaves are arrow-shaped, the leaves that float are heart-shaped with stomata on the upper side, and the underwater leaves are ribbon-like. Nonadaptive modifications often consist of all kinds of developmental disturbances, the extreme expression of which includes deformities and morphological and physiological malfunctions. These modifications occur, as a rule, in response to strong external stimuli, to which individuals of a given species are rarely exposed under normal conditions.

In contrast to mutations, modifications are not transmitted by heredity. Modifications develop in individuals of a given generation only when the conditions under which these modifications normally arise are present. However, in unicellular and occasionally multicellular organisms, prolonged modifications are found when changes in visible characters that have arisen as a result of environmental factors are retained for several generations, even after the disappearance of the inducing factors. This type of modification is apparently caused by changes in relatively stable self-reproducing cytoplasmic structures. Since they are nonhereditary, modifications have no direct evolutionary significance. If, however, a phenotype formed as a result of modification has a high adaptive value, the phenotype may become fixed in evolution only through the selection of those mutants that retain a given modification, but discard other modifications of a given character.

REFERENCES

Lobashev, M. E. Genetika, 2nd ed. Leningrad, 1967.
Shmal’gauzen, I. I. Faktory evoliutsii. Moscow, 1968.

N. V. TIMOFEEV-RESOVSKII, V. I. IVANOV and V. A. MGLINETS

modification

1. A written amendment to the contract document signed by both parties.
3. A written or graphic interpretation issued by the architect.
4. A written order for a minor change in the work, 1 issued by the architect.

modification

An alteration or change meant to rectify faults or shortcomings or which offers improved capability. A modification involves changes in the design of equipment or components.
References in periodicals archive ?
This facility, which also has parking for more than 100 trucks, becomes Fontaine's ninth US modification centre.
The study reveals a previously unknown but essential function of an mRNA modification in regulating NSC self-renewal.
Harianto, "Robust optimization of cylindrical gear tooth surface modifications within ranges of torque and misalignments," Journal of Mechanical Design, vol.
De Crecy-Lagard had previously discovered many of the genes required for the synthesis of RNA modifications known as queuosine and archeosine, which are found in microorganisms and are derived from a common precursor called preQ0.
By building parameterization mathematical model and selecting modification parameters with regularity, we attained the modification curves which correspond to all parameters.
He added that the majority of modifications revolved around tuning engines for extra horsepower and adding loud exhausts.
Of those, 666,446 modifications -- or approximately 84 % -- have been done through the company's own programs, WFC said.
Categories: March 2, 2011, Accountability, Authority to borrow from Treasury, Evaluation criteria, Foreclosures, Home Affordable Modification Program (HAMP), Homeowners loans, HOPE Hotline, Housing programs, Mortgage loans, Mortgage programs, Noncompliance, Performance measures, Program evaluation, Program management, Quality assurance, Reporting requirements, Requirements definition, Troubled Asset Relief Program (TARP)
911's software meets all the HAMP, NON-HAMP, and HAFA requirements ensuring that all of their clients achieve the best mortgage loan modification possible.
In the Home Affordable Modification Program servicer report, for the month of May, Bank of America had 142,824 active trial modifications in progress.
Bank of America Corp (NYSE: BAC) has announced that it has completed 160,000 mortgage modifications in the first half of 2010.
discussing the modifications. He said the "deal is in the framework of

Full browser ?